Optical cable with improved tracking resistance
View Patent ↗The present invention is concerned with an optical cable with improved tracking resistance comprising at least one optical fiber and an outer sheath which comprises a polymeric material, characterized in that the polymeric material forms a matrix for the sheath and consists of a multimodal olefin polymer obtained by a coordination catalyzed polymerization, and in that the total composition of the sheath comprises 15–40% by weight of a metal hydroxide, preferably magnesium hydroxide and/or aluminium hydroxide, and 0.01–0.9% by weight of carbon black.
1. Optical cable with improved tracking resistance comprising at least one optical fibre and an outer sheath which comprises a polymeric material, characterized in that the polymeric material forms a matrix for the sheath and is consisting of a multimodal olefin polymer obtained by coordination catalyzed polymerization, and in that the total composition of the sheath comprises 15–40% by weight of magnesium hydroxide and/or aluminium hydroxide and 0.01–0.9% by weight of carbon black.
2. Optical cable according to claim 1 , characterized in that said matrix for the sheath is consisting of a multimodal ethylene polymer.
3. Optical cable according to claim 2 , characterized in that said ethylene polymer has a density of 0.870–0.970 g/cm3 and a MFR2 of 0.01–10 g/min.
4. Optical cable according to claim 1 , characterized in that said polymer has MWD of 3–12.
5. Optical cable according to claim 1 , characterized in that said polymer is a bimodal polymer.
6. Optical cable according to claim 2 , characterized in that said ethylene polymer comprises an ethylene polymer fraction selected from
(a) a low molecular weight ethylene polymer having a density of 0.860–0.975 g/cm3 and an MFR2 of 50–5000 g/10 min, and
(b) a high molecular weight ethylene polymer having a density of 0.870–0.950 g/cm3 and an MFR2 of 0.01–10 g/10 min.
7. Optical cable according to claim 2 , characterized in that at least one fraction of said ethylene polymer is a copolymer which was polymerized with at least one comonomer selected from the group consisting of propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene.
8. Optical cable according to claim 2 , characterized in that said ethylene polymer comprises 35–55% by weight of a low molecular weight ethylene polymer component and 65–45% by weight of a high molecular weight ethylene polymer component.
9. Optical cable according to claim 1 , characterized in that the total composition of the sheath comprises 20–30% by weight of magnesium hydroxide and/or aluminium hydroxide.
10. Optical cable according to claim 1 , characterized in that the magnesium hydroxide and/or aluminium hydroxide has a nominal particle size of 1.4–1.8 μm.
11. Optical cable according to claim 1 , characterized in that the total composition of the sheath comprises 0.1–0.8% by weight of carbon black.
12. Optical cable according to claim 1 , characterized in that the carbon black has a nominal particle size of 10–30 nm.
13. Optical cable according to claim 1 characterized in that it has a tracking resistance of at least 15 h at 62.3% tracking propability level.
14. Optical cable according claim 2 , characterized in that said polymer has MWD of 3–12.
15. Optical cable according claim 3 , characterized in that said polymer has MWD of 3–12.
16. Optical cable according to claim 2 , characterized in that said polymer is a bimodal polymer.
17. Optical cable according to claim 3 , characterized in that said polymer is a bimodal polymer.
18. Optical cable according to claim 4 , characterized in that said polymer is a bimodal polymer.
19. Optical cable according to claim 3 , characterized in that said ethylene polymer comprises an ethylene polymer fraction selected from
(a) a low molecular weight ethylene polymer having a density of 0.860–0.975 g/cm3 and an MFR2 of 50–5000 g/10 min, and
(b) a high molecular weight ethylene polymer having a density of 0.870–0.950 g/cm3 and an MFR2 of 0.01–10 g/10 min.
20. Optical cable according to claim 4 , characterized in that said ethylene polymer comprises an ethylene polymer fraction selected from
(a) a low molecular weight ethylene polymer having a density of 0.860–0.975 g/cm3 and an MFR2 of 50–5000 g/10 min, and
(b) a high molecular weight ethylene polymer having a density of 0.870–0.950 g/cm3 and an MFR2 of 0.01–10 g/10 min.